1. Field of the Invention
This invention relates to an anti-spin/anti-drift module for use with a xe2x80x9cplug-inxe2x80x9d or xe2x80x9cplug-typexe2x80x9d railway car door and more particularly to an anti-spin/anti-drift module including first and second ratchets wherein the first ratchet has an odd number of ratchet teeth and the second ratchet has an even number of ratchet teeth.
2. Description of the Prior Art
Compression-sealing xe2x80x9cplug-inxe2x80x9d or xe2x80x9cplug-typexe2x80x9d doors are commonly provided for railway freight cars where an ambient sealing of the interior is desired, a typical case in point being refrigerated railway cars. Such doors often have a gear-operated door frame engaging mechanism coupled to be driven by rotation of a handle affixed to a pinion shaft which operates the mechanism to alternatively sealingly close the door, or alternatively to unlock it. These mechanisms are inherently powerful, and when the door is compressingly sealed, a significant reverse torque is imparted to the handle as a result of the compression forces. Such a reverse torque can also arise from a number of other factors, such as a shifted load of product inside the car leaning against the door, or the force of the door""s own weight when the car is tilted to lean outward. Handles are routinely secured against counter-rotation in the door-opening direction by handle locking mechanisms of one sort or another. To open the door, however, the handle lock must be released. If, at that time, or at any other time during rotation of the handle in the door-opening direction, the operator should lose control of the handle, the handle will frequently spin, resulting in a highly dangerous condition to the operator, and occasionally resulting in broken bones.
An anti-spin device for use with xe2x80x9cplug-inxe2x80x9d or xe2x80x9cplug-typexe2x80x9d railcar doors is described in U.S. Pat. No. 4,920,894, a patent owned by the assignee of this invention. U.S. Pat. No. 3,660,938 discloses a dual brake-type drive mechanism which is an anti-spin/anti-drift type of mechanism. The anti-spin/anti-drift mechanism disclosed in U.S. Pat. No. 3,660,938 includes first and second ratchets having the same number of ratchet teeth provided on the outer peripheries thereof. First and second gravity-operated ratchet pawls are in engagement with the ratchet teeth on the first and second ratchets, respectively. When the unit of the ""938 patent is installed in a plug-in door, the mechanism of the ""938 patent provides an anti-spin function to prevent handle backspin when opening the door and an anti-drift function to prevent the door from drifting into the car once the door is open. However, with the door of the ""938 patent in the open position, as the operator begins to close the door against the gasket seal, if the operator releases the handle when the ratchet pawl is disengaged from the anti-spin ratchet, the handle may violently spin like a propeller. This occurs if the ratchet pawl is on top of the ratchet tooth instead of being engaged into the tooth of the anti-spin ratchet.
An anti-spin/anti-drift module is described for attachment to a railway car plug-in door locking mechanism which releasably locks the door. The module comprises a pinion shaft with the outer end thereof extending through the outer surface of the railway car door. An operating handle is attachable to the outer end of the pinion shaft for operating the same. A back plate is secured to inner end of the pinion shaft and has at least a pair of spaced-apart arcuate slots formed therein. The pinion shaft is provided with an externally threaded portion thereon outwardly of the back plate. A pinion shaft sleeve is threadably mounted on an externally threaded portion of the pinion shaft. A pinion gear assembly is mounted on the pinion shaft sleeve for rotation therewith and includes an outer ring-shaped plate at its outer end and an inner ring-shaped plate at its inner end. The pinion gear assembly includes an externally presented pinion gear positioned between the inner and outer plates. The pinion gear assembly includes inwardly extending dogs which are movably received by the arcuate slots in the back plate. A first ring-shaped ratchet, ratchet wheel or ratchet gear is rotatably positioned between the inner ring-shaped plate and the back plate and includes a plurality of spaced-apart ratchet teeth. Friction pads or discs are positioned on the opposite sides of the first ratchet. A second ring-shaped ratchet, ratchet wheel or ratchet gear is rotatably positioned adjacent the outer surface of the outer ring-shaped plate with the second ratchet including spaced-apart ratchet teeth. First and second ratchet pawls are in engagement with the ratchet teeth of the first and second ratchets, respectively. Friction pads or discs are positioned on opposite sides of the second ratchet. A flange is mounted on the pinion shaft for rotation therewith outwardly of the second ratchet. The ratchet teeth of the first and second ratchets face opposite directions and have different profiles. The first ratchet has an even number of ratchet teeth (20) while the second ratchet has an odd number of ratchet teeth (21). With the module of this invention, it is impossible for the handle to violently spin as described above when the car door is open and the operator begins to close the same. The uneven numbered teeth on the second ratchet permits the second ratchet pawl to stay engaged with the teeth when closing the door under load.
It is therefore a principal object of the invention to provide an improved anti-spin/anti-drift module for use with a xe2x80x9cplug-inxe2x80x9d or xe2x80x9cplug-typexe2x80x9d railcar door.
A further object of the invention is to provide an anti-spin/anti-drift module for a railcar door operating mechanism which prevents undesirable rotation of the operating handle when closing the door under load.
A further object of the invention is to provide an anti-spin/anti-drift module for a railcar door operating mechanism which includes first and second ratchets with the first ratchet having an even number of ratchet teeth and the second ratchet having an uneven number of teeth.
These and other objects will be apparent to those skilled in the art.